1. Field of the Invention
The present invention relates to a method of manufacturing a liquid jet head for discharging liquid onto a recording medium to perform recording.
2. Description of the Related Art
In recent years, an inkjet system liquid jet head has been used for creating characters and graphics by discharging ink droplets onto a recording sheet or the like, or forming a functional thin film by discharging a liquid material onto a surface of an element substrate. In the inkjet system, ink or a liquid material is supplied from a liquid tank to the liquid jet head through a supply tube, and the ink or the liquid material loaded into channels is discharged from nozzles communicating to the channels. When discharging the ink, the liquid jet head and the recording medium, onto which a pattern of the jetted liquid is to be recorded, are moved to record characters and graphics, or to form a functional thin film having a predetermined shape.
As this type of liquid jet head, a system utilizing a thickness shear mode of a piezoelectric body has been put into practical use. Nowadays, line elongation of this type of liquid jet head has been discussed. In general, a piezoelectric member for the thickness shear mode has a maximum length of 100 mm to 140 mm, and it is difficult to form a piezoelectric member having a larger size. Therefore, it is conceived that a plurality of piezoelectric members are connected so as to achieve the line elongation of the liquid jet head.
Japanese Patent Application Laid-open No. Hei 9-48132 describes an upsized ink jet printer, which is obtained by connecting piezoelectric members to elongate the entire piezoelectric member in a direction of a printing width. FIGS. 7A, 7B, and 7C illustrate an upsized piezoelectric member described in Japanese Patent Application Laid-open No. Hei 9-48132 (FIGS. 6A, 6B, and 6C of Japanese Patent Application Laid-open No. Hei 9-48132). FIG. 7A is a plan view, FIG. 7B is a sectional view, and FIG. 7C is an enlarged sectional view of an adhesive layer portion 104. A piezoelectric member 101a and a piezoelectric member 101b are adhered to each other by the adhesive layer portion 104. In a surface of an elongated piezoelectric member 101, grooves 102 and side walls 103 are formed. The grooves 102 and the side walls 103 are formed so that one of the grooves 102 is situated above the adhesive layer portion 104.
FIGS. 8A, 8B, 8C, 8D, and 8E illustrate another example of the elongated piezoelectric member described in Japanese Patent Application Laid-open No. Hei 9-48132 (FIGS. 2A, 2B, 2C, 2D, and 2E of Japanese Patent Application Laid-open No. Hei 9-48132). As illustrated in a top view of FIG. 8E, an adhesive layer portion 120 intersects, at an angle θ1, a width direction in which grooves 112 and side walls 113 are arranged. FIGS. 8A to 8D illustrate a method of obtaining an elongated piezoelectric body portion illustrated in FIG. 8E. Specifically, as illustrated in FIG. 8A, side surfaces of piezoelectric members A1 and A2 are adhered to each other with a shift of a length y4 in a groove direction. Subsequently, as illustrated in FIG. 8B, peripheral hatched portions of an elongated piezoelectric member A3 indicated by the dotted line are cut off. Accordingly, as illustrated in FIG. 8C, the adhesive layer portion 120 is inclined at the angle θ1 from a longitudinal direction of the elongated piezoelectric member A3. A large number of grooves are formed so as to intersect the broken line of the elongated piezoelectric member A3, and the elongated piezoelectric member A3 is cut along the broken line at the center. Accordingly, as illustrated in FIG. 8D, such an elongated piezoelectric member is obtained that the grooves 112 and the side walls 113 are formed over a range from a piezoelectric member 110a to a piezoelectric member 110b. 
In the piezoelectric member 101 illustrated in FIGS. 7A, 7B, and 7C, the piezoelectric member 101a and the piezoelectric member 101b are connected to each other by the adhesive layer portion 104. The piezoelectric member 101 has a width of 200 mm to 300 mm, and has a plate thickness of 0.5 mm to 5 mm. Therefore, it is extremely difficult to adhere end surfaces of the piezoelectric member 101a and the piezoelectric member 101b to each other. Further, due to the adhesion of the end surfaces that are small in plate thickness, the strength of the adhesive layer portion 104 is low, and it is extremely difficult to deal with electrode formation, electrode terminal connection, and the like.
Further, in the elongated piezoelectric member A3 illustrated in FIGS. 8A, 8B, 8C, 8D, and 8E, the adhesive layer portion 120 intersects the side walls 113 constituting a drive unit, and hence fluctuations in mechanical characteristics and electrical characteristics occur between the side walls 113 in which the adhesive layer portion 120 is not formed and the side walls 113 in which the adhesive layer portion 120 is formed. As a result, uniformity in ink discharge characteristics is impaired. Further, bubbles are likely to remain inside the adhesive layer portion 120, which may potentially cause leakage of ink from the bubbles.